I am checking system logs via the Console utility. I am wondering what the difference is between the console.log and system.log file?

  • I don't see a console.log file OMM. Where is the file located? Commented Feb 24, 2011 at 3:27
  • @Nathan - I goofed. This applies to pre-Snow Leopard versions. Now there is just system.log as the main system event log. Apparently, ALS spits out system.log in plain text and stores another version in a binary database format. Commented Feb 24, 2011 at 3:44

2 Answers 2


Console.log is usually written to by calls to Apple's NSLog() function call. (I can't find any other way to write to it so might be the only way) This writes to the log of the user that the app is running as

system.log is written to by the unix call syslog. syslog can be configured to write to different files and machines. system.log is a central file written to by all users.

Thus only code written specifically for OSX will write to console.log and only by the current user.

syslog is used by pure unix apps and if you want central logging.

OSX since 10.4 actually writes the logs to a database using asl

  • This is great stuff - thank you! So if I'm getting this correctly, system.log would be all the xnu/Mach/BSD system log data (UNIX subsystem), while console.log is just calls from Objective-C/Cocoa apps ? Thanks for correcting my acronym...ASL! Commented Feb 25, 2011 at 21:32
  • Not completely you can call syslog or the apple asl logging from Cocoa so anything can be in syslog
    – mmmmmm
    Commented Feb 26, 2011 at 0:26

Generally, the Console log contains log messages from processes owned by the currently logged-in GUI user, whereas the System log contains log messages from system processes owned by root or other "system accounts" (e.g. "nobody", "www", etc.).

  • Thanks! So based on my comment to @Mark above, the system accounts (running system processes), are from the UNIX layer ? Commented Feb 25, 2011 at 21:33

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